This invention relates to multiple needle tufting machines, and more particularly to a needle plate for producing low pile in a multiple needle tufting machine.
In a conventional multiple needle tufting machine, the needle plate is provided with a plurality of uniformly spaced straight fingers extending from one edge of the plate in the direction of the fabric feed, or rearward, so that each finger extends between an adjacent pair of needles. These fingers are adapted to provide a support for the portion of the base fabric in the path of the needles and are spaced to permit free reciprocation of the needles between the fingers. In a conventional multiple needle tufting machine, the needle plate fingers are uniformly spaced at the same gauge as the needles.
Furthermore, a conventional needle plate finger has a rectangular cross-section, with its short dimension transverse, and its long dimension vertical. Thus, each cantilevered needle plate finger has substantial depth to provide sufficient strength to support the base fabric as the fabric is penetrated by the needles. Moreover, the short transverse dimension of each needle plate finger is desirable so that the needles can be spaced closer together to achieve finer gauges.
However, the combined depth of the needle plate finger and the height of the looper hook bill moving across a corresponding needle below the needle plate, determines the minimum pile height of the tufted loops formed by the needles and hooks.
Generally speaking, in order to form tufted loops of low pile having as short a nap as possible, the hooks are mounted to move as closely as possible beneath the bottom surface of the needle plate fingers, and the height of the bills of the loopers is reduced to a minimum. To reduce the depth of conventional needle plate fingers, would materially reduce their strength and rigidity to a degree that the needle plate fingers would not adequately support the base fabric as it is penetrated by the needles carrying the yarns.
Examples of various types of prior art needle plates are shown in the following U.S. patents:
______________________________________ 2,975,736 J. L. Card Mar. 21, 1961 2,976,829 R. T. Card Mar. 28, 1961 3,019,748 J. L. Card Feb. 6, 1962 3,064,600 R. T. Card Nov. 20, 1962 3,241,507 G. D. Dedmon et al Mar. 22, 1966 (Base plate 62-FIG. 4) 3,361,095 J. T. Short Jan. 2, 1968 3,398,708 R. T. Card Aug. 27, 1968 ______________________________________
Both J. L. Card patents disclose typical conventional needle plates having longitudinal grooves receiving elongated needle plate fingers of rectangular cross-section having a greater depthwise dimension.
The three R. T. Card patents disclose needle plates having needle plate fingers of varying configurations to accommodate narrow gauge, staggered needles.
The Dedmond et al patent discloses a "usual base plate 62" in which the needle plate fingers appear to have been formed by milling the trailing edge of the base plate to produce long needle plate fingers of substantial depth.
The Short patent discloses a needle plate of substantial thickness having a plurality of uniquely shaped recesses in the trailing edge of the needle plate especially formed to accommodate hollow, cylindrical needles of the type through which a fluid is discharged to carry the yarn through the hollow needle and fabric.
None of the above patents disclose a needle plate which is capable of producing very low pile loops in a tufted fabric.
There has been a trend in the tufting industry toward the production of tufted fabrics having a very low, as well as dense, pile, simulating products resembling velvet. The height of the tufted loops have been reduced by reducing the height of the bills of the looper hooks, but further reduction of the pile height has been limited by the finite depth of the needle plate fingers.